1. Field of the Invention
The present invention relates to neighboring information management apparatus, neighboring information management system and method therefore, and in particular, to method of management of information of neighboring base station.
2. Description of the Related Art
Today, users of mobile terminal are increasing due to spread of smart phone, and so on. Therefore, it is also required to supply a stable service for the mobile terminal when a user moves.
The neighboring information which is an important item for an area plan is planed on the basis of a distance between base stations and a direction of sector when the cell is planed. Since this method of plan is performed before establishment of a base station, it would not be possible to consider a user environment of an actual field.
Although a field measurement by vehicle is practiced for a confirmation of a user environment, the measurement is limited to data of course possible for the vehicle to measure, and so the measurement becomes a reproduction of a special user environment. Therefore, although it would be no problem for a measurement of a radio environment of a field, a reproduction of a movement of a mobile terminal such as a hand over (HO) would be difficult, and so the amount of data for examination of the neighboring information becomes insufficiency.
In addition, it is necessary to obtain time and cost to repeat driving the same route, and so on for obtaining statistical data. Although a measurement by walking or a measurement in indoor can reproduce further user environment compared with the measurement by vehicle, the course possible to measure would be limited often to special as same as the measurement by vehicle. Also in this case, precise reproduction of the user environment would be difficult, and then it would be necessary to obtain the user's data via network for the area plan.
Further, Uncontrolled HO is a movement by the mobile terminal to hand over with a target base station (destination station of the hand over) with transmission of RNG-REQ (Ranging Request) to the target base station without preparation phase of the hand over. However, there is a problem with the Uncontrolled HO that it requires more HO latency than a common hand over. Uncontrolled HO occurs regardless of registration of neighboring information between the serving station (source station of the hand over) and the target base station. However, if the neighboring information is registered, the number of the Uncontrolled HO can be reduced in comparison with the case it not registered.
The art regarding the Uncontrolled HO and the controlled HO is described in the Patent document 1 (the Japanese Patent Laid-Open No. 2009-182549) and the Patent document 2 (the Japanese Patent Laid-Open No. 2009-060449). The controlled HO is a hand over procedure in which the mobile terminal negotiates with the base station being connected and then it switches the base station when it moves.
On the other hand, the Uncontrolled HO is an urgent recovery procedure used when the communication between the mobile station and the base station being connected is cut off before the mobile station finishes the controlled HO. Then the Uncontrolled HO is a hand over procedure in which the mobile station is connected with the base station being possible to connect on the basis of the signal strength without a hand over procedure between the mobile station and the base station being connected.
The above-mentioned Uncontrolled HO occurs regardless of the registration of the neighboring information between the serving base station and the target base station. However, it is a problem for the Uncontrolled HO that the Uncontrolled HO requires more HO latency than a common hand over. On the other hand, the number of the Uncontrolled HO can be reduced more by the registration of neighboring information than by the non-registration of neighboring information.